Mr. Simon, an Ethiopian who is part of the Nuer ethnic group, went to a hospital in the western town of Gambela recently to visit his nephew, who was injured when members of the Murle ethnic group crossed into Ethiopia from South Sudan to steal cows and kill hundreds of Nuer villagers.

For better or worse, relief organizations often chalk up their biggest fund raising successes during major humanitarian crises like the famine in east Africa.

The Center on Philanthropy estimates that American nonprofit aid groups received $1.9 billion in cash and in-kind gifts after the Asian tsunami of 2004, and $1.4 billion during the year after the earthquake that decimated Haiti in January 2010.

How much would it cost to prevent a famine? We don’t know exactly, but one answer is surely this: Much less than it would cost to save lives after famine hits. The relief group Oxfam estimates that emergency relief in famines costs seven times as much as preventing the disaster to begin with.